Tips

Correctly size and position the widgets¶

It is almost always a bad idea to use fixed sizes. This will lead to portability issues, especially on high-DPI screens.

Instead of using fixed pixel sizes, it is recommended to use sizes relative to the font size, aka “em” units.

To achieve this, you should multiply your positions and sizes by ImGui::GetFontSize() (C++), or imgui.get_font_size() (Python).

In order to make this simpler, the HelloImGui::EmToVec2 (C++) or hello_imgui::em_to_vec2 (Python) function below can greatly reduce the friction: it transforms a size in “em” units to a size in pixels.

Example with Python:

from imgui_bundle import imgui, hello_imgui

def gui():
    imgui.button("A button", hello_imgui.em_to_vec2(10, 2))  # 10em x 2em button

Example with C++:

#include "imgui.h"
#include "hello_imgui/hello_imgui.h"

void gui() {
    ImGui::Button("A button", HelloImGui::EmToVec2(10, 2)); // 10em x 2em button
}